Effect of low initial C/N ratio on aerobic composting of swine manure with rice straw.

Two pilot composting experiments were conducted to investigate the effect of low initial C/N ratio on the composting of swine manure with rice straw by measuring physical and chemical parameters. The results showed that the thermophilic duration of bin 1 and bin 2 was long enough to satisfy the sanitary standard, and swine manure could reach maturity. Bin 1 containing larger amount of swine manure and less amount of rice straw showed a higher nitrogen loss (8%), shorter thermophilic phase, and longer maturity time (about 2 weeks) than bin 2. However, economical analysis showed a lower initial C/N ratio (20) could reduce 172 kg rice straw per ton fresh swine manure than a higher C/N ratio (25), and more swine manure could also be treated. Therefore, a low initial C/N ratio (20) could be suggested in the composting of swine manure with rice straw.